IMPORTANT TO KNOW! --DAY ONE-- WIRELESS STANDARDS --802.11 notes-- *Managed by IEEE LAN/MAN standards committee *Wifi alliance handles interoperability testing --802.11a-- (wifi 1) *launched 1999 *operates in 5ghz range *it can use other frequencies with special licensing *54 megabits per second *Smaller range than 802.11b *high frequency is absorbed by objects on the way --802.11b-- (wifi 2) *Also launched in 1999 *Operates in 2.4ghz *11 megabits per second * better range than 802.11a(Less absorbtion problems) *more frequent conflict(baby monitor, cordless phone,bluetooth)-not commontly seen today --802.11g-- (wifi 3) *An upgrade from 802.11b *launched june 2003 *operates in the 2.4 ghz range *54 megabits per second ( similar to 802.11a) *backwards compatible with 802.11b *same 2.4 ghz frequency conflict problems as 802.11b --802.11n (wifi 4) *The update from 802.11a,802.11b,802.11g *launched october 2009 *operates at 5ghz and/or 2.4 ghz (40 mHz channel width) *600 megabits per second ( 40 mHz mode with 4 antennas) *802.11n uses MIMO (Multiple input-Multiple output)(multiple transmit and receive antennas --802.11ac (wifi 5) *Approved in January 2014 *Significant improvements over 802.11n *operates in the 5Ghz band *Less crowded, more frequences(up to 160Mhz channel bandwitdth) *Increased channel bonding (Larger bandwidth usage) *Denser signaling modulation(faster data transfers) *Eight Mu-Mimo downlink streams *Twice as many streams as 802.11n *Nearly 7 gigabits per second --802.11ax-- (wifi 6) *Approved in February 2021 *The successor to 802.11ac/wifi 5 *Operates at 5Ghz and/or 2.4Ghz *20,40,80 and 160 Mhz channel width *1,201 mrgabits per second per channel *A relatively small increase in throughput *Eight Bi-Directional MU-MIMO streams *Orthogonal frequency-division multiple access *Works similar to cellular communication *Improves high density installations --Functions of MDM (Mobile device management)-- *Device configuration - Remotely set device settings like passwords,security policies,wifi connectors and app restrictions. *Application management - Conttrol which apps can be installed and updated on devices including white/blacklisting specific apps *Security updates - Push out security patches and OS updatges to device automatically *Data protection - Remotely wipe sensitive data from lost pr stolen devices *Device tracking - Locate lost devices using GPS capabilities *compliance monitoring -Ensure devices adhere to comapany policies and industry regulations HTTP - HYPERTEXT TRANSFER PROTOCOL/PORT 80 (web browser/web server) HTTPS - HYPERTEXT PROTOCOL SECURE/PORT 443 (web browser/we server) SSL - SECURE SHELL/PORT 22 (secure remote access) FTP - FILE TRANSFER PROTOCOL/PORT 21 (transfering of files) SMTP - SIMPLE MAIL TRANSFER PROTOCOL/PORT25 (sending mail messages/outbound) DNS - DOMAIN NAME SYSTEM/PORT 53 (dns client-dns server) POP3 - POST OFFICE PROTOCOL VERSION 3/PORT 110 (retrieve mail from server) IMAP - INTERNET MESSAGE PROTOCOL/PORT 143 (access and manage stored emails) RDP - REMOTE DESKTOP PROTOCOL/PORT3389 (remote access and control other devices) TELNET - PORT 23 (execute commands on its commandline) NTP - NETWORK TIME PROTOCOL/PORT 123 (accurate time/date) BGP - BORDER GATEWAY PROTOCOL/PORT 179 (used by routers to exchange routing information) ISAKMP - INTERNET SECURITY ASSOCIATION AND KEY MANAGEMENT PROTOCOL/PORT 500 (establishes secure vpn tunnel) LDAP - LIGHTWEIGHT DIRECTORY ACCESS/PORT 389 (usernames, passswords & other details stored) SIP - SESSION INITIATION PROTOCOL/PORT 5060/5061 (channel for voip call on pc and mobile) SYSLOG - PORT 514 (way to convert system event logs from various sources in a network) -- RAID -- (REDUNDANT ARRAY OF INDEPENDENT DISKS) *They're also inexpensive disks *different Raid levels *Some redundant, Some not -- RAID 0 -- (STRIPING) *File blocks are split between two or more physocal drives *High performance *data written quickly *No redundancy *A drive failure breaks the array *RAID 0 is ZERO redundancy -- RAID 1 -- (MIRRORING) *File blocks are duplicated between two or more physical drives *High disk utilization *Every file is duplicated *Required disk space is doubled *High redundancy *Drive failure does not affect data availability -- RAID 5 -- (Striping with Parity) *File blocks are striped *Along with parity block *Requires atleast three disks *Efficient use of disk space *Files aren't duplicated, but space is still used for parity *High redundancy *Data is available after drive failure *parity calculation may affect performance -- RAID 10(1+0) -- (A stripe with mirrors) *The speed of striping, The redundancy of mirroring *The bet of both worlds *Need atleast 4 drives -- DAY TWO -- Difference between LCD,LED & OLED- AMOLED & MINI-LED *Mini LED - Utilizes smaller LED backlights fro improved brightness and dimming compared to standard LED/LCD. *LCD - Displays use a backlight to illuminate liquid crystals -Liquid crystal display/Used liquid crystal display to control the amount light passing through a backlighyt, Creating an image on the screen *LED - Displays use of LED lights as the backlight for an LCD panel -Light emitting diode/provides better color accuracy and energy efficiency comapred to older LCD backlights *OLED - Displays have individual pixels that emit their own light, allowing for much deeper blacks and superior contrast compared to LCD and LED technologies/Excellent viweing angles -Organic light emitting diode *AMOLED - Active matrix light emitting diode(often seen in smartphones, high refresh rates & fast response times -Inverter is a device that converts direct current power(DC)from a battery into alternating current(AC) Power, which is a type of power most households appliance need to function -Rectify/Rectifier change AC to DC = Straightens the direction of thr current by allowing it to flow only one direction\ *CPU - Central processing unit is the main component of a computer that controls the flow of data and instructions also known as thr main processor --SCREEN FAILURES-- *Lid switch problem, Loose connection, Video adapter, Inverter problem, flex connector, the display itself, power connection --KEYBOARD FAILURES-- * Sticky keys, Damaged keyboard, Loose connection --CONNECTORS-- *Flex connector - Connection used in piping systems to absorb variation *SATA CABLES - Used for connecting drives -15pin is the power & 7pin is for data *SO-DIMM - Small outline dual in line memory module -smaller version of a standard DIMM used primarily in laptops and other compact devices where space is limited *Regular standard DIMM - Used for desktops -Bigger in size & requires more space -Random access memory (RAM) -- CELLULAR CARDS -- *WWAN : WIRELESS WIDE AREA NETWORK -These can be informal or external -M.2 is prefered form factor as it offers 4G network connectvity -M.2 size is 2230 (22mm Wide & 30mm LOng) -M.2 used to be called next generation form factor (NGFF) -USB is a common external option(Try 3.0 blue ports/better) -Express cards & PCMCIA Cards can help get celluar network in older laptops -These cards typically have one notch *For Wifi and Bluetooth, M.2 combo cards are common which have two noyches comapred to a cellular card. -Check compatibility to install these -Two connectors for antenna's -WLAN auto config & bluetooth support services *A PCIe Card -Peripheral component interconnect express card -An expansion card tha connects to a computer's motherboard using a PCIe slot, allowing users to add functionalities like graphics processing, networking, storage or other capabilities not already intergrated into the motherboard itself - essentially a way to upgrade or add features to a computer by plugging in a specialised card into a dedicated slot. *COMMON USES ARE : -Graphics card: For enhaced gaming or professional graphics applications -Network adapters: To improve network connectivity -Solid state drive: For faster storage options -- DAY THREE -- COMAPRE AND CONSTRAST MOBILE DEVICES - TABLETS *IPS(IN PLANE SWITCHING) - Allows for wider viewing in tablets *Quad extended graphics Array(QXGA) - Has a esolution of 2048(across) x 1536(width) *4:3 Aspect ratio(Has a little more space & height) *1.85 Ghz ARM-BASED CPU (Advanced risk machine) lower performance *LPDDR4 RAM(LOWER POWER DOUBLE DATA RATE) -8.827Mah -32.4 watt/hour (these two mean 10 hours of typical use max for battery) MOBILE DEVICES -6.0 INCH(18:9) -2880 x 1440 *2.45 ARM BASED CPU (SNAPDRAGON 835)(64BIT SYSTEM ON A CHIP) *4GB LPDDR4 RAM *32,64.128 OR 256 GB flashing memory(Similar to SDDs) *Multitouch screen(Capacitive screen) *Lithium-ION polymer battery WEARABLE TECHNOLOGIES *SMART WATCHES, HEADPHONES, FITNESS TRACKERS, GLASSES, SMARTPHONES, SMART SHOES, RING, CLOTHES. -- WIRELESS CONNECTIONS -- *Bluetooth -Includes headsets, earbuds, smartwatches & more -Class two is the most common allowing for communications up to 33 feet. -Uses the 2.4Ghz -Unlincesed ISM(INDUSTRIAL,SCIENTIFIC AND MEDICAL)BAND. -Same as 802.11 -Short range, Most consumer devices operate to about 10meters -Indystrial bluetooth can communicate over 100 meters *NFC (NEAR FIELD COMMUNICATON) via radio frequency/touch devices together -Allows for close proximity communication with encryption support -13,56MHz (Slower than bluetooth) 100 - 400 kb/s. -Two way wireless communication -Builds on RFID, Which is mostly one way.(RADIO FREQUENCY IDENTIFICATION) -payment systems, Online wallets & major credit cards.-Bootstrap for other wireless devices -Helps with bluetooth pairing -Access token identity card *IR (INFRARED) Smartphones/Tablets -IR blasters were common for a long time -Abandoned by many companies in 2017 *Mobile Hotspot (Wireless) -Allows other systems to share the smartphones internet connection -Can incur fees! *USB TETHERING -Sharing wired internet connection -Wifi is disabled during Tether --PROTECTING A PHONE-- *Insurance , Anti-Malware, Encryption, Locator programs, Remote wipe programms ** NOTE: WE HAVE A HOST & PERIPHERAL DEVICES ** -Host: Controlling other devices -Peripheral: Being controlled by other devices(Depending on the connection) *OTG - DEVICES THAT CAN OPERATE AS A HOST OR PERIPHERAL -- MOBILE EMAIL -- PROTOCOL - ORIGINAL PORT - SECURE PORT -SMTP 25 456/587 -POP3 110 995 (Makes use of SSL(Secure socket layer) -IMAP 143 993(Makes use of TLS( Transport layer security) *The two are security features on port 995/993 -- SECURITY TYPE -- *SSL -Less secure than TLS -Used to encrypt data transmitted over the internet -Developed by Netscape -Port 443 *TLS -More secure than SSL -Addresses security vulnerabilities present in the older SSL protocols -Used to encrypt data transmitted over the internet -Enhanced security features -Port 443 -- DAY FOUR -- RADIO AND ID *At first cellphones used GSM (Global system for mobile communication) for voice calls and GPRS for sending/transmitting data -Then Edge was used to attain 3G speeds. -4GB and LTE speeds are possible with IMT-Advanced requirement.(International mobile telecommunications enhanced) -5G is currently being deployed(ITU IMT - 2020 STANDARD, 20GB/S) -Airplane mode disables any and all of these (3G,4G,5G,LTE & EDGE) *PRL (PREFFERED ROAMING LIST) -A DB of service provider radio information -Used with CDMA networks *Baseband updates -Used with GSM -Also called Radio firmware -Without a connection to a cell tower, Updates can not be done *ISP (Internet service provider) *IMEI (International mobile station equipment identity) *CDMA (Code division multiple access) *IMSI (International mobile subscriber identity) *SIM (Subscriber identity module) *GPRS (General packet radio dervice Difference between PRIVATE & PUBLIC IP ADDRESS *PRIVATE IP ADDRESS -Used within a local network(Home office) -Not accesible from the internet *Provides security by keeping internal traffic private *PUBLIC IP ADDRESS -Assigned by ISP -Unique and accessible from anywhere on the internet *Used to access websites and online services -- SYNCHRONISATION METHODS -- *SYNC to cloud ( Google drive, Dropbox, One drive) uploading files to be accessible *Mutual authentication for multiple services ( using gmail to sync all app information) *SYNC to desktop/Laptop -Usually done by USB -Often requires an MTP connection done by USB MTP(Media transfer protocol) PTP(Photo transfer protocol) -SYNC between mobile devices *Can be done via OTG USB or Via WIFI Or NFC *Software requirements to install sync apps to PC(Make sure your system is compatible to install these applications) *SYNC to automobile - Using your vehocle to access your device info like calls , music, photos and messaging -- DNS ( DOMAIN NAME SYSTEM) -- * Converts names to IP addressed & Vice versa -Usually managed by ISP or enterprise IT department (A critical source) -- DHCP (Dynamic Host configuration Protocol) -- *Automatic IP address configuration *Very common service ( available on most home routers) *Enterprise DHCP will be redundant (Usually running on cemtral servers) -- File server -- * Centralised storage of documents, spreadseets, videos, pictures and any other file(A fileshare) *Standard system of file management. -SMB(Server message block) Apple filing protocol(AFP)etc. *The front end hides the protocol(Copy, delete, rename etc. -- Print Server -- *Connect a printer to the network(Provide printing services for all network devices) *May be software in a computer(computer is connected to a printer) *May be built in to the printer(Network adapter and software) *Uses standard printing protocols(SMB server message block) *IPP(Internet printing protocol) *LDP(Line printer Daemon) -- MAIL SERVER --